1. Field of the Invention
The present invention relates to an image processing apparatus, an image forming system, and a computer-readable storage medium.
2. Description of the Related Art
Conventionally, some image forming apparatuses have been developed to print images using a transparent developer besides the toners in four colors of CMYK (for example, see Japanese Patent No. 3473588). By the use of a transparent developer, a visual effect, or a tactual effect, on the surface of a recording medium (referred to as surface effect) is realized. Furthermore, forming an image using a transparent developer allows forming of a transparent image used for anti-falsification, anti-forgery, and such.
When a display device, a printing apparatus, or the like outputs a color image such as a graphic image and a character image and draws a diagonal line, a jagged and step-like portion (referred to as alias) appears. As a process to smooth out the alias portion, an anti-aliasing process that performs density correction on each pixel is known (see Japanese Patent No. 3142550).
On a drawing area to add a surface effect provided by a transparent developer, smoothing of an alias portion is achieved when an anti-aliasing process is performed. However, when the type of a surface effect for the drawing area is represented by a density value, a surface effect different from the specified type of the surface effect may be provided by the density correction in the anti-aliasing process. Accordingly, it has been configured such that the anti-aliasing process is performed on a drawing area of a color image but the anti-aliasing process is not performed on a drawing area to add a surface effect. Even though the specified type of the surface effect is not changed, this may in turn result, when the drawing area of the color image and the drawing area to add the surface effect are placed one on top of the other, in disagreement in the shape of end portions of the respective drawing areas.
Therefore, there is a need for an image processing apparatus, an image forming system, and a computer-readable storage medium that can suppress, when a drawing area of a color image and a drawing area to add a surface effect are placed one on top of the other, the shapes of end portions thereof from being in disagreement by an anti-aliasing process, and that can add a desired glossy effect to the area.